scholarly journals Potential of Smartphone SfM Photogrammetry to Measure Coastal Morphodynamics

2019 ◽  
Vol 11 (19) ◽  
pp. 2242 ◽  
Author(s):  
Marion Jaud ◽  
Matthieu Kervot ◽  
Christophe Delacourt ◽  
Stéphane Bertin
Keyword(s):  
Standard Deviation ◽  
Structure From Motion ◽  
Sandy Beach ◽  
Low Cost ◽  
Laser Scanner ◽  
Reference Dataset ◽  
Mean Error ◽  
Participatory Science ◽  
Coastal Cliff

With recent advances in photogrammetric processing methods and sensor technologies, smartphones represent a new opportunity of mainstream, low-cost sensor, with a great potential for Structure-from-Motion (SfM) photogrammetry, and in particular for participatory science programs or citizen observatories. Keeping in mind the application in citizen observatories, three smartphone models (Galaxy S7®, Lumia 930® and iPhone 8®) and a bridge camera were compared (separately and in combination) for coastal applications: A coastal cliff and a sandy beach. Various acquisition protocols, at different distances from a cliff face and using “linear” or “fan-shaped” capture mode, were also assessed in their efficiency. A simultaneous Terrestrial Laser Scanner (TLS) survey provided a reference dataset to assess the quality of the SfM reconstructions. Satisfactory reconstructions (mean error < 5 cm) of the cliff face were obtained using all smartphone models tested. To measure the cliff face, fan-shaped capturing mode allowed a quicker image acquisition on site and better results (mean error of 1.3 cm with a standard deviation of 0.1 cm at 20 m from the cliff face) than linear capturing mode (mean error of 2.5 cm with a standard deviation of 21.8 cm), provided that the distance to the cliff face is sufficient to ensure a good image overlap. To obtain satisfactory results over beaches, we show that it is preferable to have high-angle shots of the study area, which may limit the applicability of the method for certain sites.

scholarly journals RTK GNSS-Assisted Terrestrial SfM Photogrammetry without GCP: Application to Coastal Morphodynamics Monitoring

2020 ◽  
Vol 12 (11) ◽  
pp. 1889 ◽  
Author(s):  
Marion Jaud ◽  
Stéphane Bertin ◽  
Mickaël Beauverger ◽  
Emmanuel Augereau ◽  
Christophe Delacourt
Keyword(s):  
Standard Deviation ◽  
Low Cost ◽  
Laser Scanner ◽  
Satellite System ◽  
Mean Error ◽  
Ground Control Points ◽  
Participatory Science ◽  
Gnss Network ◽  
Global Navigation Satellite

The present article describes a new and efficient method of Real Time Kinematic (RTK) Global Navigation Satellite System (GNSS) assisted terrestrial Structure-from-Motion (SfM) photogrammetry without the need for Ground Control Points (GCPs). The system only requires a simple frame that mechanically connects a RTK GNSS antenna to the camera. The system is low cost, easy to transport, and offers high autonomy. Furthermore, not requiring GCPs enables saving time during the in situ acquisition and during data processing. The method is tested for coastal cliff monitoring, using both a Reflex camera and a Smartphone camera. The quality of the reconstructions is assessed by comparison to a synchronous Terrestrial Laser Scanner (TLS) acquisition. The results are highly satisfying with a mean error of 0.3 cm and a standard deviation of 4.7 cm obtained with the Nikon D800 Reflex camera and, respectively, a mean error of 0.2 cm and a standard deviation of 3.8 cm obtained with the Huawei Y5 Smartphone camera. This method will be particularly interesting when simplicity, portability, and autonomy are desirable. In the future, it would be transposable to participatory science programs, while using an open RTK GNSS network.

Color Acquisition, Management, Rendering, and Assessment in 3D Reality-Based Models Construction

2018 ◽  
pp. 1338-1380
Author(s):  
Marco Gaiani
Keyword(s):  
Structure From Motion ◽  
Low Cost ◽  
Laser Scanner ◽  
3D Models ◽  
Color Management ◽  
Simultaneous Processing ◽  
Reflectance Modeling ◽  
3D Acquisition ◽  
Acquisition Management ◽  
Shape Data

This chapter presents a framework and some solutions for color acquisition, management, rendering and assessment in Architectural Heritage (AH) 3D models construction from reality-based data. The aim is to illustrate easy, low-cost and rapid procedures that produce high visual accuracy of the image/model while being accessible to non-specialized users and unskilled operators, typically Heritage architects. The presented processing is developed in order to render reflectance properties with perceptual fidelity on many type of display and presents two main features: is based on an accurate color management system from acquisition to visualization and more accurate reflectance modeling; the color pipeline could be used inside well established 3D acquisition pipeline from laser scanner and/or photogrammetry. Besides it could be completely integrated in a Structure From Motion pipeline allowing simultaneous processing of color/shape data.

Color Acquisition, Management, Rendering, and Assessment in 3D Reality-Based Models Construction

2015 ◽  
pp. 1-43
Author(s):  
Marco Gaiani
Keyword(s):  
Structure From Motion ◽  
Low Cost ◽  
Laser Scanner ◽  
3D Models ◽  
Color Management ◽  
Simultaneous Processing ◽  
Reflectance Modeling ◽  
3D Acquisition ◽  
Acquisition Management ◽  
Shape Data

In this chapter are presented a framework and some solutions for color acquisition, management, rendering and assessment in Architectural Heritage (AH) 3D models construction from reality-based data. The aim is to illustrate easy, low-cost and rapid procedures that produce high visual accuracy of the image/model while being accessible to non-specialized users and unskilled operators, typically Heritage architects. The presented processing is developed in order to render reflectance properties with perceptual fidelity on many type of display and presents two main features: is based on an accurate color management system from acquisition to visualization and more accurate reflectance modeling; the color pipeline could be used inside well established 3D acquisition pipeline from laser scanner and/or photogrammetry. Besides it could be completely integrated in a Structure From Motion pipeline allowing simultaneous processing of color/shape data.

scholarly journals ON OUTLIER DETECTION IN A PHOTOGRAMMETRIC MOBILE MAPPING DATASET

2015 ◽  
Vol XL-3/W2 ◽  
pp. 227-233 ◽  
Author(s):  
C. Taglioretti ◽  
A. M. Manzino ◽  
T. Bellone ◽  
I. Colomina
Keyword(s):  
Outlier Detection ◽  
Focal Length ◽  
Low Cost ◽  
Laser Scanner ◽  
Urban Canyon ◽  
Forward Search ◽  
Mobile Mapping

Various types of technology are used for Terrestrial Mobile Mapping (TMM) such as IMU, cameras, odometers, laser scanner etc., which are integrated in order to determine the attitude and the position of the vehicle in use, especially in the absence of GNSS signal i.e. in an urban canyon. <br><br> The aim of this study is to use only photogrammetric measurements obtained with a low cost camera (with a reduced focal length and small frames) located on the vehicle, in order to improve the quality of TMM solution in the absence of a GNSS signal. It is essential to have good quality frames in order to solve this problem. In fact it is generally quite easy to extract a large number of common points between the frames (the so-called ‘tie points’), but this does not necessarily imply the goodness of the matching quality, which might be uncorrected due to the presence of obstacles that may occlude the camera sight. The Authors used two different methods for solving the problem of the presence of outliers: RANSAC and the Forward Search. <br><br> In this article the Authors show the results obtainable with good quality frames (frames without occlusions) and under difficult conditions that simulate better reality.

scholarly journals Structure from motion (SfM) photogrammetry as alternative to laser scanning for 3D modelling of historical monuments

2020 ◽  
Vol 5 (2) ◽  
Author(s):  
Omar Al Khalil
Keyword(s):  
Structure From Motion ◽  
Laser Scanning ◽  
Low Cost ◽  
Laser Scanner ◽  
Digital Camera ◽  
Point Clouds ◽  
3D Modelling ◽  
3D Point Clouds ◽  
Historical Monuments ◽  
Culture Heritage

During the past few years, new developments have occurred in the field of 3D photogrammetric modeling of culture heritage. One of these developments is the expansion of 3D photogrammetric modeling open-source software, such as VisualSfM, and cost-effective licensed software, such as Agisoft Metashape into the practical and affordable world. This type of SfM (Structure from Motion) software offers the world of 3D modelling of culture heritage a powerful tool for documentation and visualization. On the other hand, low-cost cameras are now available on the market. These cameras are characterized by high resolution and good quality lens, which makes them suitable for photogrammetric modelling. This paper reports on the results of the application of a SfM photogrammetry system in the 3D modelling of Safita Tower, a medieval structure in Safita, north-western Syria. The applied photogrammetric system consists of the Nikon Coolpix P100 10 MP digital camera and the commercial software Agisoft Metashape. The resulted 3D point clouds were compared with an available dense point cloud acquired by a laser scanner. This comparison proved that the low-cost SfM photogrammetry is an accurate methodology to 3D modeling historical monuments. 

scholarly journals Measurement of Rock Joint Surfaces by Using Smartphone Structure from Motion (SfM) Photogrammetry

Sensors ◽  
2021 ◽  
Vol 21 (3) ◽  
pp. 922
Author(s):  
Pengju An ◽  
Kun Fang ◽  
Qiangqiang Jiang ◽  
Haihua Zhang ◽  
Yi Zhang
Keyword(s):  
Structure From Motion ◽  
High Speed ◽  
Low Cost ◽  
Rock Joint ◽  
Laser Scanner ◽  
3D Models ◽  
Roughness Coefficient ◽  
Joint Surfaces ◽  
Photogrammetric Method ◽  
The Mean

The measurement of rock joint surfaces is essential for the estimation of the shear strength of the rock discontinuities in rock engineering. Commonly used techniques for the acquisition of the morphology of the surfaces, such as profilometers and laser scanners, either have low accuracy or high cost. Therefore, a high-speed, low-cost, and high-accuracy method for obtaining the topography of the joint surfaces is necessary. In this paper, a smartphone structure from motion (SfM) photogrammetric solution for measuring rock joint surfaces is presented and evaluated. Image datasets of two rock joint specimens were taken under two different modes by using an iPhone 6s, a Pixel 2, and a T329t and subsequently processed through SfM-based software to obtain 3D models. The technique for measuring rock joint surfaces was evaluated using the root mean square error (RMSE) of the cloud-to-cloud distance and the mean error of the joint roughness coefficient (JRC). The results show that the RMSEs by using the iPhone 6s and Pixel 2 are both less than 0.08 mm. The mean errors of the JRC are −7.54 and −5.27% with point intervals of 0.25 and 1.0 mm, respectively. The smartphone SfM photogrammetric method has comparable accuracy to a 3D laser scanner approach for reconstructing laboratory-sized rock joint surfaces, and it has the potential to become a popular method for measuring rock joint surfaces.

scholarly journals Integrated Georeferencing of LiDAR and Camera Data Acquired from a Moving Platform

2014 ◽  
Vol XL-3 ◽  
pp. 191-196
Author(s):  
F. Liebold ◽  
H.-G. Maas
Keyword(s):  
Data Acquisition ◽  
Structure From Motion ◽  
Error Propagation ◽  
Low Cost ◽  
Laser Scanner ◽  
Sequential Data ◽  
Polynomial Functions ◽  
Laser Scanners ◽  
Moving Platform ◽  
Orientation Parameters

This paper presents an approach for modeling the trajectory of a moving platform equipped with a laser scanner and a camera. In most cases, GNSS and INS is used to determine the orientation of the platform, but sometimes it is impossible to use GNSS, especially indoor applications should be mentioned here. INS has a bad error propagation without GNSS. In addition, the accuracy of GNSS and low-cost INS is limited and often not equivalent to the accuracy potential of laser scanners. For the camera, there exists the well-known alternative to obtain the orientation parameters via triangulation, for instance employing structure-from-motion techniques. But it is more challenging to find an alternative for the laser scanner, because of its sequential data acquisition. In the approach shown here, we propose to use a camera in combination with structure-from-motion techniques as the basis for determining the laser scanner trajectory parameters. For that purpose, we use piece-wise models for the trajectory through polynomial functions, supported by time-stamped matches between laser scanner and camera data.

scholarly journals TRIPOD—A Treadmill Walking Dataset with IMU, Pressure-Distribution and Photoelectric Data for Gait Analysis

Data ◽  
2021 ◽  
Vol 6 (9) ◽  
pp. 95
Author(s):  
Justin Trautmann ◽  
Lin Zhou ◽  
Clemens Markus Brahms ◽  
Can Tunca ◽  
Cem Ersoy ◽  
...  
Keyword(s):  
Gait Analysis ◽  
Low Cost ◽  
Ground Truth ◽  
Treadmill Walking ◽  
Reference Dataset ◽  
Data Pipeline ◽  
Analysis Laboratory ◽  
Measurement Units ◽  
Walking Speeds

Inertial measurement units (IMUs) enable easy to operate and low-cost data recording for gait analysis. When combined with treadmill walking, a large number of steps can be collected in a controlled environment without the need of a dedicated gait analysis laboratory. In order to evaluate existing and novel IMU-based gait analysis algorithms for treadmill walking, a reference dataset that includes IMU data as well as reliable ground truth measurements for multiple participants and walking speeds is needed. This article provides a reference dataset consisting of 15 healthy young adults who walked on a treadmill at three different speeds. Data were acquired using seven IMUs placed on the lower body, two different reference systems (Zebris FDMT-HQ and OptoGait), and two RGB cameras. Additionally, in order to validate an existing IMU-based gait analysis algorithm using the dataset, an adaptable modular data analysis pipeline was built. Our results show agreement between the pressure-sensitive Zebris and the photoelectric OptoGait system (r = 0.99), demonstrating the quality of our reference data. As a use case, the performance of an algorithm originally designed for overground walking was tested on treadmill data using the data pipeline. The accuracy of stride length and stride time estimations was comparable to that reported in other studies with overground data, indicating that the algorithm is equally applicable to treadmill data. The Python source code of the data pipeline is publicly available, and the dataset will be provided by the authors upon request, enabling future evaluations of IMU gait analysis algorithms without the need of recording new data.

scholarly journals A LOW-COST AND PORTABLE SYSTEM FOR 3D RECONSTRUCTION OF TEXTURE-LESS OBJECTS

2015 ◽  
Vol XL-1-W5 ◽  
pp. 327-332 ◽  
Author(s):  
A. Hosseininaveh ◽  
R. Yazdan ◽  
A. Karami ◽  
M. Moradi ◽  
F. Ghorbani
Keyword(s):  
Structure From Motion ◽  
Laser Light ◽  
Low Cost ◽  
Laser Scanner ◽  
Point Clouds ◽  
3D Modelling ◽  
Optical Methods ◽  
Stepper Motor ◽  
Light Sources ◽  
Portable System

The optical methods for 3D modelling of objects can be classified into two categories including image-based and range-based methods. Structure from Motion is one of the image-based methods implemented in commercial software. In this paper, a low-cost and portable system for 3D modelling of texture-less objects is proposed. This system includes a rotating table designed and developed by using a stepper motor and a very light rotation plate. The system also has eight laser light sources with very dense and strong beams which provide a relatively appropriate pattern on texture-less objects. In this system, regarding to the step of stepper motor, images are semi automatically taken by a camera. The images can be used in structure from motion procedures implemented in Agisoft software.To evaluate the performance of the system, two dark objects were used. The point clouds of these objects were obtained by spraying a light powders on the objects and exploiting a GOM laser scanner. Then these objects were placed on the proposed turntable. Several convergent images were taken from each object while the laser light sources were projecting the pattern on the objects. Afterward, the images were imported in VisualSFM as a fully automatic software package for generating an accurate and complete point cloud. Finally, the obtained point clouds were compared to the point clouds generated by the GOM laser scanner. The results showed the ability of the proposed system to produce a complete 3D model from texture-less objects.

scholarly journals BENDING THE DOMING EFFECT IN STRUCTURE FROM MOTION RECONSTRUCTIONS THROUGH BUNDLE ADJUSTMENT

2017 ◽  
Vol XLII-2/W6 ◽  
pp. 235-241 ◽  
Author(s):  
L. Magri ◽  
R. Toldo
Keyword(s):  
3D Reconstruction ◽  
Structure From Motion ◽  
Detection Method ◽  
Low Cost ◽  
Critical Issue ◽  
Bundle Adjustment ◽  
Real Word ◽  
A Posteriori ◽  
Novel Method

Structure from Motion techniques provides low-cost and flexible methods that can be adopted in arial surveying to collect topographic data with accurate results. Nevertheless, the so-called “<i>doming effect</i>”, due to unfortunate acquisition conditions or unreliable modeling of radial distortion, has been recognized as a critical issue that disrupts the quality of the attained 3D reconstruction. In this paper we propose a novel method, that works effectively in the presence of a nearly flat soil, to tackle <i>a posteriori</i> the doming effect: an automatic ground detection method is used to capture the doming deformation flawing the reconstruction, which in turn is wrapped to the correct geometry by iteratively enforcing a planarity constraint through a Bundle Adjustment framework. Experiments on real word datasets demonstrate promising results.

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